1. Field of the Invention
This invention relates to a connecting structure for connecting a filler hose or an air hose with a mating member in an automobile.
2. Description of the Related Art
Recently, as the filler hose and so on for an automobile, a resin hose, a metallic hose and a hose combined with both hoses which are excellent in a gasoline permeability-proof character, have been widely used, instead for a rubber hose. For example, a hose connecting structure in which one end of the resin hose is detachably connected to the mating member has been known in Japanese Unexamined Patent Publication No. 5-329956.
That is, the prior hose connecting structure disclosed in the above Japanese Unexamined Patent Publication No. 5-329956 is, as shown in FIGS. 1 and 2, comprised of a hose 10 and a mating member 45 with which the hose body 10 can be connected. The hose body 10 is blow-formed (blow-molded) by a resin material, and is constructed by a hose body 15 including straight end portions 28 extending straightly at both ends thereof and an engaging member 34 attached to an outer surface of at least one straight end portion of the hose body. Here, an intermediate portion 20 having a bellow portion 22 is extended between the straight end portions 28.
On an outer surface of the tubular straight end portion 28, seal grooves 24 into which annular sealing members 23 are fitted are formed at a tip or front end, an annular large-diameter portion 25 having a large diameter is formed at a rear end, and an annular groove 26 for fitting is formed at an intermediate portion, respectively. The annular large-diameter portion 25 located at the rear end of the straight end portion 28 is formed to make an inner diameter of the intermediate portion 20 larger than an inner diameter of the straight end portion 28, thereby maintain a large flowing amount of the filler.
The engaging member or connecting member 34 includes an annular base portion 34a, a plurality of arm portions 34b, and first engaging portions 34c. Each of the arm portion 34b extends parallel to the straight end portion 28 toward the front end thereof via a support portion standing up from the annular base portion 34a radially outwardly. Each of the first engaging portion 34c is formed at a free end of the arm portion 34b to directed radially inwardly. The engaging member 34 is attached to the straight end portion 28 by forcedly fitting the annular base portion 34a into the ring groove 26, and is protruded radially outwardly.
On the other hand, a metallic or a resin pipe 45 as the mating member includes tubular opened end portion 44 and an annular second engaging portion 42. The opened end portion 44 has an inner diameter slightly larger than an outer diameter of the straight end portion Z8 of the resin hose 10, and the annular second engaging portion 42 is formed by folding back an opened tip end of the opened end portion 44 axially outwardly to be protruded from an outer surface of the opened end portion 44 radially outwardly.
When the resin hose 10 is connected with the pipe 45, the straight end portion 28 is inserted into the opened end portion 44. As insertion of the straight end portion 28, the arm portions 34b of the engaging member 34 are elastically or resiliently deformed radially outwardly once by the second engaging portion 42, and then returned radially inwardly when it has passed by the second engaging portion 42, whereby the first engaging portion 34c engages with the second engaging portion 42.
By the way, in the above connecting structure the intermediate portion 20 of the hose body 15 is preferably formed by a thin tubular wall to increase flexibility of the hose body 15.
However, the hose body 15 is usually produced by a blow-forming when it is made of the resin material, and is produced by a metal liquid bulge forming at the end portion and/or the bellow partially by a thin tube drawn into a constant thickness when it is made of the metallic material. For this reason, making only the intermediate portion 20 thinner than the both straight end portions 28 is difficult in both of the resin hose and metallic hose, that is, to increase the flexibility of intermediate portion 20, the whole hose body 15 needs to be thinned. Thus, the straight end portions 28 are also thinned to reduce strength or rigidity thereof.
As a result, when the straight end portion 28 of the hose body 15 is connected to the opened end portion 44 of the mating member 45 and the fluid is flown therethrough, an axially central portion of the straight end portion 28 bulges radially outwardly by the fluid pressure. In this way, the sealing character by the sealing member 23 between the straight end portion 28 and the opened end portion 44 may be deteriorated, and the engagement of the first engaging portion 34c with the second engaging portion 42 may be disengaged.
Also, when this connecting structure is used under a cold environment below 10.degree. C., the axially central portion of the straight end portion 28 may be shrunk radially inwardly, so that the disadvantages that the sealing character by the sealing member 23 between the straight end portion 28 and the opened end portion 44 may be deteriorated and the engagement of the first engaging portion 34c with the second engaging portion 42 may be disengaged are caused.